Manufacture of artificial threads, filaments, and the like



March 28, 1939. E. A. MORTON 2,152,620,

MANUFACTURE OF ARTIFICIAL THREADS. FIL-AMENTS, AND THE LIKE Filed Feb. 29, 1936 I INVENTOR ERIC ANDREW MORTON by Firs affar'ne'gs Patented M... 28, 1939 UNITED STATES MANUFACTURE OF ARTIFICIAL, THREADS, I

FILAMENTS, AND THE LIKE Eric Andrew Morton, Coventry, England, assignor to Courtaulds, Limited, London, England, a

British company Application February 29, 1936, Serial No. 66,490 In Great Britain March 1, 1935 6 Claims. 34-24) In the specification of Letters Patent No. 1,736,681 it is stated that if a cake of artificial threads, such as is obtained by collecting the thread in a centrifugal spinning box, is washed .6 and then dried while still in the annular form,

the thread on the outside of the cake dries under a tension which is greater than that to which the thread on the inside of the cake is subjected, owing to the fact that the inside layers can contract 10 readily while the outside layers do not have the same opportunity of contracting. The said specification No. 1,736,681 describes and claims the step of deforming the cake so that it is no longer annular in shape, but so that practically all parts of the threads in the cake are accorded free opportunity to contract on drying, without being subjected to undue tension.

Various methods of drying cakes have been proposed, some of which aim at the avoidance of a production of strained threads on the outside of the cake. For example it has been proposed to cause the drying air to flow through the material forming the cake, either from the inside to the outside or from the outside to the inside, the cake being either left in or taken out of the spinning box. It has also been proposed .to lead the drying medium practically exclusively along the freely exposed inner walls of the central apertures of the cake. It has also been proposed to dry the cakes preliminarily on their surfaces and then to expose them to an air current which is forced through the thread layers. It has also been pro posed to place the cakes on a perforated peg and to blow air at high pressure through the cakes in order to loosen them and produce passages between the threads, and then to continue drying with the use of large quantities of air at lower pressure. It has also been proposed to dry the whole cake from the inner to the outer side and then turn the cake inside out and continue to dry from the inner to the outer side. Another proposal consists in drying the cake from the inside or outside thereof, then wetting it and drying it in the opposite direction, i. e. from the outside or inside respectively.

I have now found that dry cakes of artificial threads which are practically free from strain, or are considerably less strainedthan the thread in cakes which have been dried by the application of warm air-to all surfaces thereof, can be obtained by introducing the thread. into the centrifugal box so that the thread crosses itself at an angle of at least 12 and then, after the cakes have received suitable treatment with one or more liquids, supplying hot air or other gas slowly into the hollow centres of the cakes, which cakes are placed one above the other without separating members on a perforated tube which is spaced from the inner walls of the cakes, while a weighted plate or its equivalent rests on the top of the uppermost cake, the plate being enabled to descend and compress the cakes as they dry, the air or other gas supplied to the centre of the cakes thus being compelled to pass evenly through the cakes from the inside to the out- 10 side so that the moisture is gradually displaced from the inside layers to and through the outside layers, the said outside layers being the last to lose their moisture. According to this invention the hot air or other gas is caused to pass 15 slowly and evenly through the cake from the inside to the outside, that is to say in such manner that during the drying process no path is allowed to form through which the drying air or gas can pass more rapidly than through the 20 remainder of the cake. If such path be allowed to form, the thread adjacent the path dries more rapidly than the rest, thus tending to produce strain which it is the object of the present invention to avoid. It should be particularly noted 25 that the process according to this invention is not applicable tocakes during the formation of which the funnel which guides the threads into the spinning box traverses too slowly up and down the centre of the box. On the contrary, in order that a cake may be suitably treated according to this invention, it is necessary that the threads should cross one another at an angle of at least 12. A suitable angle for this purpose is, for example, 15, but the invention is not 35 limited to the treatment of cakes in which the threads cross at this particular angle. This crossing of the threads in the cake ensures that the drying air can be passed through the cake without disturbing it or producing uneven pas- 40 sages through it. In carrying out the process of this invention, a number of cakes, for example 'four or six, are formed into a vertical pile with their axes coinciding, the lower surface of the lowercake and the upper surface of the top 45 cake being closedby means such as plates in order to prevent the escape of the hot air which is introduced into the hollow space inside the cakes through a pipe leading through either the upper or lower plate or both. The upper plate is ar- 50 ranged so that it is free to move and remain in contact with the top cake as the cakes contract during the drying. The air may conveniently be supplied at a temperature of. from to-100 centigrade, and at the commencement of the 66 y it reaches the outside of the cake. As the process of removal of moisture from the cake proceeds, the cake becomes more permeable to the air and the air leaving the outside of the cake becomes warmer andcontains less water. 7

When the process according to this invention is employed for the drying of cakes which have been deformed according to the method described in the aforementioned specification No. 1,736,681, it is preferred'to carry out the deforming of the cakes after they have been placed on the tube or pipe, through which the hot air is subsequently supplied.

The accompanying drawing shows diagrammatically an example of apparatus suitable for carrying out one method according to this invention, but the invention is not limited to the said method or to the particular example of apparatus.

Referring to the drawing, A is a case or chest on top of which rests a plate B to which the per,- forated pipe or tube C is attached. Cakes D are placed around the tube C,..the lower cake resting upon the plate B while the other cakes form a vertical pile abovethe lowest cake. A sleeve E fits loosely around the upper part of the tube C and is provided at its lower end with a flange F which rests on the upper surface of the topmost cake, and a weight G rests on the flange F. Hot air enters the case A and passes up the tube C and through the perforations thereof and thence through the walls of the cakes D, carrying the moisture with it in such a manner that the inner surface of the cake is dried first and the outer surface last. As the cakes gradually dry they contract and the flanged sleeve E and the weight G- descend and maintain contact between the flange F and the uppermost cake D, between the plate B and the lowermost cake D and between the intermediate cakes D, so that no great loss of air is sustained.

' that the threads cross one another at an angle of at least 12", whereby hot gas supplied to said free inner layers is compelled to pass evenly through the cakes from the inside to the outside so that the moisture is gradually displaced through the outside layers, the said outside layers being the last to lose their moisture, which comprises placing the wet'cakes, one above the other without separating members ona support which closes the bottom of the hollow interior of the column thus formed of the cakes, said column surrounding a perforated tube, closed at one end, which tube has an exterior diameter smaller than the interior diameter of the free inner layers of the cakes, resting a weighted plate on the top of the .uppermost cake, the plate being enabled to descend freely by gravity and compress the cakes as they dry and supplying hot gas slowly through the perforated tube to the free inner layers at the hollow centres of the cakes. v

2. In the manufacture of artificial thread, wherein cakes formed by the centrifugal box spinning process are subjected to liquid treatment, the improvements which comprise: first controlling the traverse during spinning to cause the threads of the cake to cross each other at an angle of at least 12; later aligning and directly contacting the wet cakes from said liquid treatment into a hollow vertical column without'sep arators and with the inner layers of the cakes unsupported and free to contract, closing the ends of said column, supplying gaseous dryin'g medium into the hollow interior of said column at points distributed axially therealong and spaced inwardly from the inner layers of said cakes whereby the same are free to contract upon drying, and

the angle of winding compels even passage of said gaseous medium through said cakes gradually displacing the moisture through the outside layers, and weighting said column to take up axial shrinkage and maintain sai d even passage during the drying operation.

3. In the manufacture of artificial thread, wherein cakes formed by the centrifugal box spinning process are subjected to liquid treatment, the improvements which comprise: first controlling the traverse during spinning to cause the threads of the cakes to cross each other at an angle of at least 12; later aligning the wet cakes from said liquid treatment into a vertical column of contacting cakes without separators and without any obstruction to the inner layers of said cakes, deforming said column by forming therein aligned radial indentations whereby the outer layers of said cakes are free to contract upon drying, closing the ends of said column, supplying gaseous drying medium into the hollow interior of said column at points distributed axially therealong and spaced inwardly from the inner layers of said cakes whereby the same are free to contract upon drying, and the angle of winding compels even passage of said gaseous drying medium through said cakes gradually displacing the moisture through the outside layers, and weighting said column to take up axial shrinkage and maintain said even passage of aseous drying medium during the drying opera tion.

4. In the manufacture of artificial thread, wherein cakes formed by the centrifugal box spinning process are subjected to liquid treatment, the cakes being given a corrugated outer contour before drying, and being dried after removal from the centrifugal box, the improvements which comprise aligning and contacting the wet cakes from said liquid treatment into a vertical column without separators which would prevent thread to threadcontact between the cakes and without radial support for the inner layers of said cakes, closing the ends of said column, supplying hot air into the hollow interior of said column at points distributed axially therealong and spaced inwardly from the inner layers of said cakes whereby the same are free to contract upon drying, and causing the hot air to pass through the cake from the inside to the outside, so that moisture is gradually displaced from the inside layer of the cake to and through the outside layer, the said outside layer being the last to loseits moisture.

5. In the manufacture and production of artificial thread, wherein cakes are formed by centrifugal box spinning in which the thread is projected within a rotating confining wall, leaving the inner layers of the cake free, and such cakes are subjected to liquid treatment and subsequent drying in cake form, the process of reducing drying strains and irregularities which comprises first controlling the traverse of said thread projection to cause the threads of the cakes to cross each other at an angle of at least 12 whereby relatively open cake structure is produced which permits even passage of drying medium therethrough but which contracts axially for a substantial portion of its height upon drying, removing said relatively open structure cakes from said confining walls and subjecting them to liquid treatment, placing the wet cakes from said liquid treatment one above the other in direct contact without any separating members therebetween on a support which closes the bottom of the hollow vertical column formed by said cakes, the inner layers of said cakes remaining radially unsupported and thereby free to contract annularly upon drying, closing the top of said column and applying weight thereto suflicient to maintain said top closure and to cause thread to thread contact between said cakes, and otherwise free to descend by gravity with the axial contraction of said cakes'for the total height of said contraction, supplying gaseous heating medium under pressure into the hollow interior of said column at points distributed axially therealong and angularly therewithin and spaced inwardly from the free inner surface of said cakes, whereby said gaseous heating medium fills said hollow interior and is applied under said pressure uniformly over the entire free inner surface of said column, the angularity of the crossing of the threads subjected to said uniformly distributed pressure causing said medium to pass evenly through the cakes without disturbing the threads or producing uneven passages therethrough, and the free gravity descent of said weighted closure automatically taking up axial contraction of said column and thereby maintaining said even passage during the drying operation.

6. In the manufacture and production of artificial thread, wherein cakes formed by the box spinning process are subjected to liquid treatment and subsequent drying in cake form, the process of reducing drying strains and irregularities which comprises first controlling the traverse during the box spinning to cause the threads of the cakes to cross each other at an angle of at least 12, thereafter placing the wet cakes from said liquid treatment one above the other in direct thread to thread contact without any separating members on a support which closes the bottom of the hollow vertical column thereby formed of said cakes, the inner layers of said cakes being radially unsupported and thereby free to contract upon drying, deforming said column by forming thereinaligned radial indentations whereby the outer layers of said cakes are free to contract upon drying, closing the top of said column and applying thereto a weight concentric therewith, supplying gaseous drying medium into the hollow interior of said column at points distributed axially therealong and angularly therebetween and spaced inwardly from the free inner layers of said cakes and under pressure sufficient to force said gaseous drying medium through said cakes to the outside thereof, the angularity of the crossing of the threads causing even passage of said gaseous drying medium through said cakes without disturbing the threads thereof or producing uneven passages therethrough, said weight being free to descend by gravity with the contraction of said column for a material part of its original height and thereby automatically maintain said even passage of said medium during the drying operation.

ERIC ANDREW MORTON. 

